Universal DRO based on Arduino Nano - shDRO
Ladies and gentlemen, hello.
In this article I will talk about the development of a device for taking readings from digital lines and other sensors placed on turning and milling machines.
Development is not yet completed and will be described what has been done so far.
')
Who cares, welcome under cat.
ShDRO characteristics:
(crossed out functionality that has not yet been implemented)
Modular scheme:
The device consists of the following modules:
Schematic diagram:
In the next part, I will describe the logic of shDRO, describe the currently available console commands, and also lay out the first version of the firmware.
The second part of.
In this article I will talk about the development of a device for taking readings from digital lines and other sensors placed on turning and milling machines.
Development is not yet completed and will be described what has been done so far.
')
Who cares, welcome under cat.
Why the development, but not a finished product.
I have two machines for metal (Chinese): milling and turning.
From time to time I make products of varying degrees of complexity on them (I am not a turner or a milling machine operator, this is just a hobby). And, if the product is difficult, then you had to take a calculator in hand and calculate the course of the cutter or cutter. And also, if the cutter / cutter stroke turned out to be quite large, then it was necessary to count the revolutions of the caliper handles, which frankly strained. As a result, I thought about the DRO (digital calipers were bought for a long time just for this purpose, but the lack of time was constantly delaying production).
Before I started developing my DRO, I had to answer two questions regarding the appropriateness of my own design:
I answer myself.
Yes, there are many products on the market, both domestic and foreign, with different prices and with different functionality. The same Ali offers ready-made DRO with three optical lines at a price of about 13,000 rubles. - very low price for such a device. But the manufacturing process itself is interesting to me, so the option “bought and put” disappeared.
Answering the second question, I put myself in the place of a person who will assemble the device according to some description, and what he should do. Namely:
And only after these steps, you get a finished product. Each step takes some time, and since a person is lazy and impatient (in the good sense of these words), he wants to see the result of the device operation as soon as possible, even if it is intermediate. And I nevertheless decided to develop my device so that a person even at the very beginning of the assembly process, saw the intermediate results of his work.
Now it was necessary to choose a board for implementation.
Choose between Arduino based on Atmega and STM.
I am a top-level programmer, but I had to program Atmega and MSP-430 microcontrollers for work, I was not familiar with STM. Therefore chose Atmega. I chose the cheapest board (or not? I just had them) Arduino Nano based on Atmega328 microcontroller.
From time to time I make products of varying degrees of complexity on them (I am not a turner or a milling machine operator, this is just a hobby). And, if the product is difficult, then you had to take a calculator in hand and calculate the course of the cutter or cutter. And also, if the cutter / cutter stroke turned out to be quite large, then it was necessary to count the revolutions of the caliper handles, which frankly strained. As a result, I thought about the DRO (digital calipers were bought for a long time just for this purpose, but the lack of time was constantly delaying production).
Before I started developing my DRO, I had to answer two questions regarding the appropriateness of my own design:
- why not buy a finished product?
- There are many DRO projects in the network, of different levels of complexity, with detailed descriptions of making it yourself. So why not collect one of them?
I answer myself.
Yes, there are many products on the market, both domestic and foreign, with different prices and with different functionality. The same Ali offers ready-made DRO with three optical lines at a price of about 13,000 rubles. - very low price for such a device. But the manufacturing process itself is interesting to me, so the option “bought and put” disappeared.
Answering the second question, I put myself in the place of a person who will assemble the device according to some description, and what he should do. Namely:
- purchase the necessary components: processor, display, buttons and small things such as resistors, capacitors, stabilizers, etc. (without this, of course, nowhere);
- depending on the complexity of the project, make / purchase a printed circuit board;
- then solder everything and flash the processor;
- after, make work on the bugs;
And only after these steps, you get a finished product. Each step takes some time, and since a person is lazy and impatient (in the good sense of these words), he wants to see the result of the device operation as soon as possible, even if it is intermediate. And I nevertheless decided to develop my device so that a person even at the very beginning of the assembly process, saw the intermediate results of his work.
Now it was necessary to choose a board for implementation.
Choose between Arduino based on Atmega and STM.
I am a top-level programmer, but I had to program Atmega and MSP-430 microcontrollers for work, I was not familiar with STM. Therefore chose Atmega. I chose the cheapest board (or not? I just had them) Arduino Nano based on Atmega328 microcontroller.
ShDRO characteristics:
(crossed out functionality that has not yet been implemented)
- Arduino Nano board, Atmega328 processor;
- 12 independent channels / ports of Arduino to which readers are connected;
- Each channel has properties: Type (CLKin, DATAin, Ain, Bin, etc.), EI (Enable Interrupt), IL (Interrupt Level), Inv (invoiced signal);
- maximum number of devices connected: 6;
- each device can be assigned one or more channels of the 12 available;
- protocol support: 24BIT,
21BIT,BCD7, BIN6, quadrature signal,periodic signal from the tachometer(it is possible to add new protocols); - console: allows using the terminal program to configure and test shDRO during the assembly and operation;
- in console mode, a “pseudo” logic analyzer is implemented, which allows you to read the levels of channels specified in the console and determine the exchange protocol. The maximum number of samples is 256, the minimum measured time between samples is 8µs. At least one analyzed channel must be configured to interrupt;
Modular scheme:
The device consists of the following modules:
- three voltage regulators 5v., 3v., 1.5.v. Stabilizers on 3v. and 1.5.c. adjustable. These voltage levels are used in digital calipers (1.5v.) And in the lines iGAGING (3v.);
- 4 eight-bit seven-segment MAX7219-based indicators, cascaded to hardware SPI;
- keyboard. The keyboard consists of two resistive matrices: 2x4 and 4x4 in this case, the layout of the tracks on the board is simpler (but you can make two 3x4 matrices for someone more comfortable). Each matrix is ​​connected to the ADC channel;
The use of resistive matrices for me is a big minus, because over time, the resistance of the buttons will increase, and the voltage levels measured by the ADC will change accordingly. But the “fair” matrix simply did not have enough legs / ports on the board (for 24 buttons, 10 ports are needed). On this basis, the keyboard learning functionality is implemented in the firmware, training can be done at any time, and no connection with the terminal program is needed (the training will be written below). - a speaker connected to the hardware leg of timer 1;
- adapter board, which are designed to coordinate the levels between devices and ports of the Arduino;
- 4 DB9 female connectors (for good, you need to install 6 connectors, because shDRO supports up to 6 devices, but I did not clutter up the future rear panel of the case, assuming that three connectors will be used for the axes, and one connector will be shared between the other devices) . The connectors are very simple, with legs for soldering wires. The wires, in turn, are unsoldered to the adapter board;
The choice of this type of connector due to the following reasons: reliability (compared to USB connectors and RJ-45), a large number of conclusions and ease of soldering. And I also have one optical line with a connector of this type.
Schematic diagram:
In the next part, I will describe the logic of shDRO, describe the currently available console commands, and also lay out the first version of the firmware.
The second part of.
Source: https://habr.com/ru/post/446408/
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